Silver coin. Found on the floor of the Cloister during the Arizona Expediton '64-'66 at Guevavi.
From catalog card at the Arizona State Museum: Coin 1 ½ Real; silver. Coin is round in plan view and very thin in cross-section. Stamped design on both faces. One face has coat of arms and crown above it in the center; around edge is "CAR.III.D.G HISP.ETIND.R." Other face has crown and other symbols in center; around edge is "VTRA QUE VNUM M (stands for Mexico City, the mint) 1771 (date) F" (assayer's initial.) The "CAR III" stands for Carlos III.